1. Technical Field of the Invention
The present invention relates to a card key having a function as an electronic key and having a shape of a credit card, and in particular to a handheld card key favorable for use for vehicles.
2. Related Art
Recently, handheld electronic keys (categorized as handheld devices) have come to be available for locking or unlocking vehicle doors and/or starting engines. For example, in response to a query signal from an on-vehicle device, such an electronic key functions by transmitting an ID code specific to the vehicle to the on-vehicle device, and after verification of the ID code, automatically allows locking or unlocking of the vehicle doors subject to matching of the ID code, or allows startup of the engine.
For example, this type of electronic key is disclosed in patent documents JP-A-2007-224664, JP-A-2007-227246, JP-A-2004-134835, JP-A-2004-079796, JP-A-H07-317394 and JP-A-2004-241476. As disclose in these patent documents, an electronic key in general is configured to have a casing in which a circuit board and a battery are accommodated and hermetically enclosed using a cover. However, such a configuration necessitates an electronic key to have a large thickness and gives insufficient usability such as in carrying the electronic key. Thus, an electronic key having good usability and having a shape of a credit card (hereinafter referred to as “card key”) has been desired.
As shown in FIGS. 1 to 4, for example, in the above card key, a circuit board 101 is integrally covered with a resin material 104 for formation into a shape of a plate. The circuit board 101 is mounted with electronic parts 102 that perform radio communication with an on-vehicle device. This card key 100 is provided with a battery accommodating hole 104a having a closed cross section for accommodating a battery 105, and a key accommodating hole 104b having a closed cross section for accommodating a mechanical key 106. Also, a logo 107 of a vehicle maker is attached to the card key 100.
For example, as shown in FIG. 3, the card key 100 described above is manufactured by injection molding of a resin using a die 200. The die 200 includes a lower die 201 (core plate), an upper die 202 (cavity plate) and a slide core 203 (bush). The slide core 203 is moved rightward, as viewed in FIG. 3, passing between battery terminals 103, 103 to form the battery accommodating hole 104a. Although not shown, the die 200 also includes a slide core for forming the key accommodating hole 104b. This slide core is moved leftward, as viewed in FIG. 3, to form the key accommodating hole 104b. 
In this way, in the conventional art, the slide core 203 and the like have been used to form the battery accommodating hole 104a and the key accommodating hole 104b. For this reason, the structure of the die 200 has been unavoidably complicated, and thus, as the card key 100 becomes thinner, more manufacturing cost has been incurred. When the card key 100 is formed into a thin shape using the die 200, only a uniform design (appearance design) has been available, and thus it has been difficult to provide a variety of aesthetic designs.